Rotary wing system with ion field flow control

ABSTRACT

A rotary-wing system which generates a directed ion field to propel a fluid along a rotary-wing to control at least one boundary layer characteristic.

BACKGROUND OF THE INVENTION

The present application relates to a rotary-wing system with increasedefficiency through manipulation of a boundary layer.

A propeller system is limited in effectiveness and power density by themaximum speed achievable at the blade tip without separation and theassociated drag and vortex generation. Since the speed of the remainderof the propeller is limited by the tip speed, the overall efficiency ofthe propeller is thereby limited. Likewise, as the propeller forwardspeed changes relative to the surrounding fluid, the effective velocityand vector at the tip changes which further limits the rotational speedachievable without separation.

SUMMARY OF THE INVENTION

A rotary-wing system according to an exemplary aspect of the presentinvention includes: a rotary-wing rotatable about an axis of rotation;at least one emitter mounted to the rotary wing; and at least oneattractor mounted to the rotary wing adjacent to the at least oneemitter to generate a directed ion field therebetween to control atleast one boundary layer characteristic.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of this invention will becomeapparent to those skilled in the art from the following detaileddescription of the currently disclosed embodiment. The drawings thataccompany the detailed description can be briefly described as follows:

FIG. 1 is a schematic perspective view of a rotary-wing system with anion flow control system according to the present invention;

FIG. 2 is a sectional view of one rotary-wing illustrating the ion flowcontrol system;

FIG. 3 is a schematic representation of the fluid flow in response tothe ion flow control system;

FIG. 4 is a schematic view illustrating a change in boundary flow inresponse to operation of the ion flow control system;

FIG. 5 is a graphical view of a boundary layer characteristic inresponse to particular control levels of the ion flow control system;

FIG. 6 is a graphical representation illustrating the reduced propellerrotary-wing power requirements in response to operation of the ion flowcontrol system; and

FIG. 7 is a perspective view of one non-limiting embodiment of an aerialvehicle for use with the ion flow control system.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENT

FIG. 1 illustrates a general perspective view of a propeller system 10.The propeller system 10 includes a hub assembly 12 which supports amultiple of propeller blades or rotary-wings 14 which rotate about anaxis of rotation A. It should be understood that although a propellerblade system typical of a fixed wing aircraft is illustrated in thedisclosed embodiment, various propeller and rotor blade systemsincluding helicopters, compound rotary wing aircraft with supplementaltranslational thrust systems, dual contra-rotating, coaxial rotor systemaircraft, turbo-props, tilt-rotors, tilt-wing and fixed wing aircraft ofvarious configurations as well as fixed systems such as wind turbinesand such like will also benefit from the present invention. That is,rotary-wing as utilized herein may be any propeller blade and rotarywing which rotates about an axis of rotation.

The propeller system 10 includes an ion flow control system 16. Thesystem 16 includes a set of at least one emitter 18 and at least oneattractor 20 on each rotary-wing 14. Each of the emitters 18 and theattractors 20 in the illustrated non-limiting embodiment may be poweredfrom a power source P capable of producing, for example only, pulsed DCpower, constant DC power or an alternative power source. It should beunderstood that the duty cycle of a pulsed DC power source can beoptimized for maximum efficiency.

Referring to FIG. 2, a first emitter 18A may be located forward of arotary wing leading edge 14L and a first attractor 20A may be locatedproximate the leading edge 14L. In one non-limiting embodiment, thefirst emitter 18A may be located forward of the rotary wing leading edge14L upon a probe 22 which extends from the leading edge 14L. Similarlyand for example only, the first emitter may be positioned directly uponall or some portion of the leading edge itself. Additional emitters 18B,18C and attractors 20B, 20C sets may be positioned along an uppersurface 14U of the rotary-wing 14 to define an emitter/attractornetwork.

In one non-limiting embodiment, the emitters 18B, 18C and respectiveattractors 20B, 20C may be located in a mid-span region and trailingedge region. Still further, at least one additional emitter 18D, 18E andattractor 20D, 20E sets may be positioned along a lower surface 14M ofthe rotary-wing 14. It should be understood that other emitter/attractornetwork arrangements may alternatively or additionally be provided. Itshould further be understood that any number of sets may be mounted toeach rotary-wing 14 so as to generate a desired boundary layermodification.

Each of the emitters 18 and each of the attractors 20 may bemanufactured of an electrically conductive material such as, for exampleonly, carbon fiber material or nanotubes. Each emitter 18 operates as anion source and each attractor 20 operates as an ion collector such thatthe emitter/attractor network may be utilized to create a directed ionfield (FIG. 3). Created ions repelled by the emitter 18, drive theemitter 18 forward and ions aft while the opposite charge on therespective attractor 20 accelerates ion towards (and past) the attractorwhich accelerates the attractor 20 forward by attraction to the createdions. Such related emitter-attractor sets may be stacked for improvedefficiency.

A concentrated field around each emitter 18 ionizes the adjacentatmosphere which is accelerated towards the less concentrated attractor20 mounted further aft on the rotary-wing 14 (FIG. 3). The ions bearingthe same charge as the emitter 18 are repelled, then attracted to theattractor 20 with a diffused field insufficient to initiate ionizationbut strong enough to attract the ions generated at the emitter 18. Thisattraction both continues to accelerate the ion and accelerates thereceiver/attractor toward the created ions. Both actions add to theforward thrust of the rotary-wing. As the ions travel towards theattractor, collision with other atmospheric molecules causesacceleration of non-ionized entrained atmosphere that further increasesthe flow across the rotary-wing 14.

Through variation in boundary layer control (including reduced orreversed flow) across various portions of the rotary-wing 14, variousadditional effects such as steering, braking, increased lift, andstability may alternatively and additionally be accomplished in additionto drag reduction. As generally understood, the definition of a boundarylayer as utilized herein is a thin layer of fluid immediately next to asolid body that flows more slowly than the rest of the fluid. It shouldbe understood that although boundary layer is described herein as beingcontrolled, since the fluid adjacent the solid body such as therotary-wing is accelerated faster than the rest of the fluid, that areamay understood as not actually being part of the boundary layer asgenerally understood. In other words, the present invention does reducethe boundary layer and also affects the fluid beyond the boundary layer.

Referring to FIG. 4, the directed ion flow modifies the boundary layerflow across the rotary-wing 14. The velocity of a fluid traveling in theboundary layer prior to application of the directed ion flow isillustrated graphically on the left side of FIG. 4 as shaded region F1.The shaded region F1 represents the velocity reduction of the fluidrelative a distance from the upper surface 14U. That is, the fluid atthe top of the shaded region F1 is further away from the surface 14Uthan the fluid at the bottom of the shaded region F1.

After the directed ion flow is generated within the fluid, the boundarylayer velocity loss characteristics are altered as schematicallyillustrated in a second shaded region F2. The second shaded region F2illustrates the reduction in velocity loss of the fluid in the boundarylayer after the influence of the directed ion field. In the illustratedexample of FIG. 4, the directed ion flow directs the fluid in adirection opposing the direction of motion of the rotary wing 14. Thisresults in an increased fluid velocity and the reduced boundary layerthickness as shown in shaded region F2.

Reduction of the boundary layer has the effect of reducing the parasiticdrag and inhibiting boundary layer separation. Boundary layer separationoccurs primarily at a tip of the rotary-wing to create an air gapbetween the boundary layer and the upper surface 14U of the rotary-wing14, i.e., a wake vortex can be created which results in a decrease inperformance characteristics of the rotary-wing 14 whether driven ordriving. That is, operation of the system 16 reduces the boundary layerthickness or build up as well as inhibit flow separation to increase theefficiency thereof.

Referring to FIG. 5, the system 16 may be utilized to selectively varythe thickness of the boundary layer, the fluid flow velocity near thesurface, and the flow direction in response to adjustment of the appliedlevel of control. Representative fluid velocities and boundary layercharacteristics for no control (NO), low level control (LOW),intermediate level control (INT.) and a high level control (HIGH) areschematically illustrated. As indicated by the fluid velocities at thevarying levels of control, the higher the level of control applied, thegreater the impact on the adjacent fluid velocities and the boundarylayer thickness.

The NO control boundary layer characteristic illustrates the thicknessof the boundary layer without the application of any control (such as F₁in FIG. 4). The Y axis illustrates the boundary layer thickness. As alarger level of control is applied, the effective thickness of theboundary layer decreases and the velocity of the fluid in the boundarylayer is accelerated to match or exceed the initial fluid velocity.Varying the level of control is achieved by adjusting the strength ofthe directed ion field as in response to the level of power beingapplied across the emitter/attractor network.

Referring to FIG. 6, a reduction in rotary-wing power required at agiven operating speed with application of ionic flow control isgraphically represented. Application of ion flow control to the outersection—for example only, the outer one-third of the rotary-wing 14span—increases airflow attachment across the rotary-wing blade tip 14Twhich facilitates an increased operating speed and higher efficiency.Boundary layer control of the rotary-wing 14 also facilitates areduction in parasitic drag, reduced separation, and reduced wake drag.

When constructing a rotary-wing 14 it is typically necessary to accountfor non-optimal airflow conditions by, for example, varying forwardspeed, tip speed, and pitch. Implementing boundary layer control on thesurface of the rotary-wing 14 such as described herein minimizes theimpact of adverse conditions and allows for the rotary-wing 14 to beoperated at a higher efficiency than is possible without boundary layercontrol.

Referring to FIG. 7, an air vehicle 100 driven by an ion flow controlpropeller system 10′ offers highly efficient propulsion to provide fornearly continuous operation with solar electric power from photovoltaic(PV) cells and high power density batteries permitting both daylight andnighttime flight. The ion flow control propeller system 10′ mayalternatively or additionally be powered by a variety of electricalpower sources—photovoltaics (PVs), batteries, electrical generators, ora combination depending upon the vehicle configuration and missionrequirements.

It should be understood that relative positional terms such as“forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like arewith reference to the normal operational attitude of the vehicle andshould not be considered otherwise limiting.

It should be understood that although a particular component arrangementis disclosed in the illustrated embodiment, other arrangements willbenefit from the instant invention.

Although particular step sequences are shown, described, and claimed, itshould be understood that steps may be performed in any order, separatedor combined unless otherwise indicated and will still benefit from thepresent invention.

The foregoing description is exemplary rather than defined by thelimitations within. Many modifications and variations of the presentinvention are possible in light of the above teachings. The disclosedembodiments of this invention have been disclosed, however, one ofordinary skill in the art would recognize that certain modificationswould come within the scope of this invention. It is, therefore, to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described. For thatreason the following claims should be studied to determine the truescope and content of this invention.

1. A rotary-wing system comprising: a rotary-wing rotatable about anaxis of rotation; at least one emitter mounted to said rotary wing; andat least one attractor mounted to said rotary wing adjacent to said atleast one emitter to generate a directed ion field therebetween tocontrol at least one boundary layer characteristic.
 2. The system asrecited in claim 1, further comprising a power source to power said atleast one emitter and said at least one attractor.
 3. The system asrecited in claim 2, further comprising a controller which adjusts saidpower source in response to said at least one boundary layercharacteristic.
 4. The system as recited in claim 2, further comprisinga controller which adjusts said power source in response to at least onerotary-wing operating condition.
 5. The system as recited in claim 2,wherein said power source generates a direct current.
 6. The system asrecited in claim 2, wherein said power source generates a pulsed directcurrent.
 7. The system as recited in claim 1, wherein said at least oneboundary layer characteristic includes a boundary layer reduction, saiddirected ion field directed to propel said fluid along said rotary-wingin a direction generally opposite a rotational direction of saidrotary-wing.
 8. The system as recited in claim 1, wherein said at leastone emitter extends forward of a leading edge of said rotary-wing. 9.The system as recited in claim 1, wherein said at least one emitter andsaid at least one attractor are configured into a plurality of sets, andwherein adjacent sets of ionizers and attractors have reversed polarity.10. The system as recited in claim 1, wherein said at least one emitterand said at least one attractor are configured to prevent reverse flowof oppositely charged particles.
 11. A method of enhancing theefficiency of a rotary-wing as said rotary-wing travels through a fluidmedia comprising: ionizing a portion of the fluid media through whichthe rotary-wing travels; and accelerating the flow of ionized fluidmedia over the rotary-wing to reduce a boundary layer adjacent to therotary-wing.
 12. A method as recited in claim 11, wherein said ionizingfurther comprises: ionizing the portion of the fluid media adjacent anouter span of the rotary-wing.
 13. A method as recited in claim 11,wherein said ionizing further comprises: positioning a first emitterforward of a leading edge of said rotary-wing; and applying a firstcharge to said first emitter.
 14. A method as recited in claim 13,wherein said ionizing further comprises: positioning at least oneadditional emitter downstream of the first emitter; and applying asecond charge to the additional emitter.
 15. A method as recited inclaim 11, wherein said ionizing further comprises: positioning a firstemitter forward of a leading edge of said rotary-wing; and applying afirst charge to said first emitter.
 16. A method as recited in claim 15,wherein said ionizing further comprises: positioning at least oneadditional emitter downstream of the first emitter; and applying asecond charge to the additional emitter.
 17. A method of enhancing theefficiency of a rotary-wing as said rotary-wing travels through a fluidmedia comprising: ionizing a portion of the fluid media through whichthe rotary-wing travels; and accelerating the flow of ionized fluidmedia over the rotary-wing to accelerate the fluid media over the wingto velocities equal to or higher than the initial fluid velocityrelative to the rotary-wing.
 18. A method as recited in claim 17,wherein said ionizing further comprises: ionizing the portion of thefluid media adjacent an outer span of the rotary-wing.
 19. An airvehicle comprising: a rotary-wing system which supports a multiple ofrotary wings which rotate about an axis of rotation; at least oneemitter mounted to said rotary wing; and at least one attractor mountedto said rotary wing adjacent to said at least one emitter to generate adirected ion field therebetween to modify at least one boundary layercharacteristic.
 20. The vehicle as recited in claim 19, furthercomprising a power source to power said at least one emitter.
 21. Thevehicle as recited in claim 20, wherein said power source comprisesphotovoltaic (PV) cells.
 22. The vehicle as recited in claim 19, whereinsaid rotary-wing system comprises a propeller system.
 23. A powerextraction/generation system comprising: a rotary-wing system whichsupports a multiple of rotary wings which rotate about an axis ofrotation; at least one emitter mounted to said rotary wing; and at leastone attractor mounted to said rotary wing adjacent to said at least oneemitter to generate a directed ion field there between to modify atleast one boundary layer characteristic.
 24. The system as recited inclaim 23, further comprising a power source to power said at least oneemitter.
 25. The system as recited in claim 23, wherein said rotary-wingsystem comprises a propeller system.